Thin films of the p-type semiconductor, barium copper sulfide fluoride (BaCuSF) were deposited using pulsed laser deposition. Similar p-type conductivity in Cu2O is caused by copper vacancies. Addition of copper dopant is proposed as a method for filling the copper vacancies in BaCuSF. The films are characterized to determine quality...
TiO₂ typically crystallizes into three polymorphs: brookite, rutile, and anatase. The phase selection problem in TiO₂ is the lack of understanding what conditions cause amorphous TiO₂ to crystallize into one of its three polymorphs during an annealing process. It has been recently shown that phase selection in TiO₂ is highly...
The addition of a weather ballooning program at Western Oregon University creates research opportunities for the Science Department, allows for projects in professional development for in-service teachers, fosters a partnership with Oregon Space Grant, and creates another option for students participating in the Program for Undergraduate Research Experiences. As the...
The goal of this research is to determine whether x-ray diffraction (XRD) is a viable method for resolving ZnS thin films on Si substrates. The samples are ZnS thin films of thickness between 50nm and 100nm, on Si substrates that are 0.5mm thick.
ZnS and Si have nearly identical lattice...
A method has been developed to measure the thickness of ZnS thin films on Si using optical interference. Thin film optical interference fringes are dependent upon the thickness of the film, and for this reason the thickness can be determined by measuring reflectance spectrum of a thin film. A grating...
A new class at Oregon State, PH 317: Experimental Physics, is designed to simulate a traditional laboratory research experience for undergraduate students. Several weeks of the class is devoted to Brownian motion experiments. Although this is a common topic for undergraduate lab classes, the experiment still needed some basic exploration...
Hall measurements can be made on the unstudied alloy, Sn₁-ₓCaₓSe to determine its electrical transport properties. The Sn₁-ₓCaₓSe samples were made by laser deposition into thin films and have a variable of calcium concentration x. These samples are approximately 250 nm in thickness, were grown at 366° C and are...
Impedance spectroscopy is a method of modeling materials with equivalent circuits to determine electrical properties, such as the resistivity and the dielectric constant. We explore impedance spectroscopy, both theoretically and experimentally through applying the method to samples of BaCuS1-xSexF. Grain boundary effects were dominant in the results, and although they...
Zinc sulfide thin films on silicon wafers were analyzed for layer thickness, refractive index, and absorption using reflection spectroscopy (RS), spectroscopic ellipsometry (SE), and modeling programs. RS and refractive index values from literature were used to model film thickness based on reflection and the SCOUT modeling program was used to...
This thesis looks at the third harmonic voltage response of a small incandescent lightbulb. The third harmonic voltage, or 3 omega (3ω) voltage, arises from applying a 1ω sinusoidal voltage across a resistive material. The 3ω voltage carries with it information about the thermal conductivity of the material. A lock-in-amplifier...
The optical transition in high-fraction polymorphs of titania (TiO2) were investigated to determine the band gap behavior of the most common polymorphs—brookite, rutile, and anatase—the values of which are varied in the literature. The direct optical band gaps of brookite, rutile, and anatase, were determined to be 3.37(7)eV, 3.41(11)eV and...
The optical characterization of transparent conductive thin films is demonstrated. The basics of transparency and conductivity, as they relate to transparent conductor research, are explained. A functional model of the reflectance and transmittance of a sample film, including interference fringes, is derived from the Fresnel electric field amplitude coefficients. The...
This study used SCOUT optical modelling software to create models of the reflectance and transmittance spectra generated by mixtures of titanium dioxide (TiO2) and tin oxide (SnO2). These models enabled identification of how altering the ratio of a mixture changes the optical response. By being able to identify how altering...
Transparent conductive oxides (TCO) are at the forefront of technology with their uses in
touch screen phones and televisions, solar cells and more. Titanium dioxide and tin dioxide are two TCOs that have been studied in depth on their own, so to further explore these TCOs, this project focuses on...
The fundamental physics of turbulence in plasma is not well understood. Recent studies of the plasma deflagration accelerator in the High Temperature Gasdynamics Lab at Stanford University have demonstrated the presence of small scale instabilities that limit the lifetime of the jet/Z pinch and are not reproduced by coaxial plasma...
Semiconducting materials are of immense importance due to their presence in almost all modern devices. It is possible that the surface physics of semiconductors could be used to control the nanoscale topography and properties of these materials, ultimately creating new options for device fabrication. This could result in profound implications...
A series of seven magnesium-doped copper scandium oxide films were made by radio frequency sputtering, and intercalated at various oxygen pressures to create different oxygen concentrations in each film. The objectives of this study were to verify the p-type nature of these transparent conductive thin films, to determine the correlation...
The purpose of this project is to verify scattering mechanisms in semiconductors by measuring transport properties and producing data that reflects existing research. The Hall effect is utilized to measure the resistivity, mobility and charge carrier concentration of the semiconductors: indium tin oxide (ITO), p-type silicon, and n-type silicon. By...
Spectroscopic ellipsometry (SE) is used to characterize amorphous and crystalline thin films of TiO2. Amorphous precursor films of TiO2 are deposited by radio frequency magnetron sputtering on fused silica and silicon substrates. Annealing the amorphous precursor films induces them to crystallize into either pure or mixed phases of the three...
An experimental apparatus is modified to allow measurements of the Seebeck coefficient and resistivity to be taken simultaneously. This apparatus is designed for bulk and thin film samples between temperatures of 10 K and 300 K. The apparatus is constructed such that these simultaneous measurements do not interfere with each...